This invention relates generally to lifting assemblies and more specifically to those which are not mechanically joined so as to be independently movable and non-synchronous relative to one another.
One difficulty which has been encountered using such prior art assemblies has been that of maintaining a preferred relative vertical displacement between the article supporting arms thereof as the arms translate along their frames. This problem can occur because of the difficulty in supplying the precisely proper rate of hydraulic fluid flow to each of the lifting cylinders in the assemblies, especially where the loading on each may differ widely either because the load they are lifting is off-center or because the weight of the article being lifted is not uniformly disbursed along the horizontal plane. Whatever the reason for the difficulty, it has often been found necessary in the past to physically and mechanically tie the lifting cylinders together to insure their synchorous movement. The subject invention overcomes this and other difficulties encountered in the prior art.